The present invention relates to portable shelters, and more particularly to a collapsible shelter for use on plots of loose earth such as a sandy beach and the like.
Varieties of portable structures are known in the prior art. One type has a plurality of legs and a flexible cover member that is suspended by the legs. See, for example, U.S. Pat. No. 2,777,450 to Kramer.
A disadvantage of these structures is that the legs are hard to drive into sand sufficiently deep for properly supporting the cover, particularly when the wind is blowing. This is true whether the sand is loose and dry, requiring the legs to be driven in very deep, and when the sand is wet, requiring large driving forces for even shallow penetration of the legs into the sand.
Another disadvantage is that the legs are attached in a fixed relation to the cover, so that one cannot adjust the sag of the cover when the legs are affixed rigidly in the ground. The legs, being metal tubing, do not provide flexibility for maintaining a desired tension of the cover. Also, it is difficult to align four legs with four fixed attachment points on the cover for providing a uniformly flat smooth surface of the cover.
Another disadvantage is that vertical adjustment of the cover requires telescoping the legs. This complicates the leg construction, adding unnecessary costs to the umbrella.
A further disadvantage is that the legs must be repositioned for producing a sideshade configuration.
Thus there is a need for a portable beach sunshade that is easy to erect firmly anchored on wet or dry sand, that maintains firm and even tension on the cover, and provides a sideshade capability on any selected side without requiring leg repositioning or a reduction in overhead coverage, and permits convenient vertical adjustment without the complexity and expense of telescopic legs.